Gas turbine engines and other types of turbo-machinery are often used to drive loads such as electrical generators. Shafts connecting turbines to compressors of such gas turbine engines may be subject to axial vibrations. Conventional friction dampers in rotating parts of the engines may not work, because of high rotor speed which creates too much centrifugal force to allow the damper to slip. There is a desire to provide friction dampers to dampen gas turbine engine axial vibrations. There is a desire to provide friction dampers to dampen gas turbine engine axial vibrations of gas turbine engines and other types of turbo-machinery used to drive loads such as electrical generators.